What is the relay of non-priority loads to control the power supply system and how to use it?
Country cottage owners are often encountered with the problem of overloading a low-power cottage network that occurs when connecting various powerful techniques. Especially often there is an overload of the network in the cold season, when heating devices are added to electrical equipment. A frequent problem is to turn off the introductory circuit breaker due to overload. You can solve the problem with the help of a special device - relay disabling non-execution load.
These relays allow you to increase the number of consumers without exceeding the allowed power, and, consequently, without turning off the input circuit breaker. They are installed in the shield, and they are connected to electrocups to which various consumers are connected, broken into two groups:
- priority (chain supplying electricity lighting, refrigerator, etc.), which should not be disconnected under any circumstances;
- non-priority (warm floor, cumulative water heater, electrical heaters, etc.), which allows short-term breaks in power supply.
Such a non-execution load disconnection relay has a number of large manufacturers, such as Schneider Electric, ABB, LEGRAND.
Relay Redistribution of the load
How does the non-executive load switching relay? Consider on the example of the updated line of the LEGRAND (in the picture). A single-phase relay on currents up to 28 A continuously tracks the current flowing through it (and, respectively, power consumed) and turns off the irreducient load, for example, convector, if you enable both electrical stoves, and the power exceeds the specified value of 3.68 kW. As soon as one of the burners turn off - the electroconvector is turned on, etc. Thus, the relay allows you to use the appliances with a total capacity of 5 kW when limiting at 3.68 kW. Power limit can be changed in the range from 0 to 6.5 kW in 0.01 kW increments. This provides an adjustable time delay from 0 to 999 p. On the inclusion / disable non-execution load. The maximum current of the disconnection of the non-execution load is 16 A (4 kW). The relay is equipped with a power, current and voltage measurement unit. Information is displayed on the LCD display.
In the case when you want to control the currents of more than 28 A or when a three-phase home nutrition system is used, it is advisable to use a universal relay that can work in both single-phase and three-phase circuits. In single-phase mode, non-executive loads are divided into three groups. If the total current of priority and non-executive loads exceeds the mounted limit, the consumers connected through the contacts S1 and S2 are turned off. If the total current still exceeds the specified limit, then consumers connected to the contact relay S3 are disconnected. With a decrease in the total load, the consumers of the third group are primarily connected, and then, if there is a power supply, consumers of the first and second group.
Maximum load on the contacts of the relay of non-priority loads - 15a.
The principle of operation remains the same, but it is possible to choose an algorithm for disabling non-executive loads. Either all three groups are disconnected at the same time, when the threshold value of the total current in one of the phases is exceeded, or each group will be disconnected depending on the load in the specific phase.
Advantages that provide a non-executive load disconnecting relay:
- An increase in the number of consumers without changing the highlighted power and increase the cross section of the introductory cable;
- Preventing the shutdown of the introductory circuit breaker due to overload;
- Electricity savings due to reduced losses in the supply line.
Diagram connection of the redistribution relay
